The present invention relates to a control lever and more particularly relates to a control lever for shifting a control valve such as to effect neutral, extension, retraction, and float conditions in an extensible and retractable hydraulic actuator.
Conventional motor graders include a main frame extending forwardly from an operator station and supported at its forward end by front wheels. The main frame is elevated above the ground and located therebeneath and having a forward end universally connected to the main frame is a drawbar or sub-frame having a circle structure fixed thereto. A blade-carrying standard is mounted for rotation on the circle structure and has a blade mounted thereon for endwise shifting movement relative thereto.
For the purpose of disposing the blade in desired positions relative to the surface or material to be worked, these conventional motor graders are often provided with a plurality of hydraulic functions including extensible and retractable lift and sideshift actuators connected between the main and sub-frames, extensible and retractable blade sideshift and blade pitch actuators connected between the sub-frame and the blade, and a blade rotation function for rotating the blade carrying standard on the circle structure.
In order to reduce the operator fatigue and ensure safe operation, it is a practice to group certain of the controls so that an operator may efficiently position the blade by operating controls with one hand while steering with the other hand. Two such controls heretofore grouped are a pair of control levers which are selectively movable independently or together among four different positions for effecting neutral, extension, retraction, or float conditions in an associated one of the actuators. This arrangement has not proved to be entirely satisfactory since it is sometimes desirable to only momentarily actuate one of the lift actuators to its float condition and heretofore this has necessitated the control levers to be shifted from a beginning position to their float position and then back to their beginning position.